copper wire bonding
**Copper Wire Bonding** is a semiconductor interconnect technique using copper wire as a lower-cost alternative to gold wire, now dominant in high-volume packaging.
## What Is Copper Wire Bonding?
- **Material**: 99.99% pure copper (4N Cu) or palladium-coated copper
- **Process**: Thermosonic bonding, similar to gold but higher force/power
- **Advantage**: 90%+ cost reduction vs. gold wire
- **Challenge**: Oxidation prevention requires forming gas (N₂/H₂)
## Why Copper Wire Bonding Matters
With gold at $60+/oz vs copper at $0.30/oz, the cost savings for high-volume products like smartphones is substantial—millions of dollars annually.
```
Copper vs. Gold Wire Bonding:
Property | Gold | Copper
----------------|-----------|----------
Material cost | High | Very low
Ball hardness | Soft | Hard
Bond force | Low | 2-3× higher
Pad damage risk | Low | Higher
Oxidation | None | Requires N₂/H₂
Conductivity | Good | Better (10%)
```
**Process Requirements for Copper**:
- Forming gas atmosphere (95% N₂ / 5% H₂) or nitrogen
- Higher bonding force and ultrasonic power
- Specialized capillaries for harder material
- Enhanced FAB (free air ball) formation control